(11, 12) demonstrated that P. salmonis induces an IFN-inducible response (IRF-1, GBP-1, IFN), but CD4 overexpression and CD8b underexpression were observed, suggesting that P. salmonis modulates CD8+ T cell-driven evasion of CMI and promotes the CD4+ T cell response during the late phase of infection as a mechanism to escape host defenses (Figure 2). Here, CD4 is linked to infection.